What Is the Keto Diet?

If You've Been Considering the Keto Diet, This Might Change Your Mind

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The keto diet is gaining in popularity, but it's also "a dietitian's nightmare," Lisa Eberly said. We chatted with the registered dietitian to get her expert opinion on the trendy diet we've been hearing so much about. Spoiler alert: she's not into it.

What Is a Keto Diet?

A keto — short for ketogenic — diet is a low-carb diet, in which the body produces ketones in the liver to use as energy in lieu of carbohydrates (more on that later). Like other low-carb, high-fat (LCHF) diets, keto draws people in with its promised weight-loss results. Blogs, Pinterest, and Instagram have been lighting up with "keto recipes" and meal plans, but that doesn't mean it's actually good for you.

"When you eat something high in carbs, your body will produce glucose and insulin," Lisa explained. Glucose and insulin, at proper levels, are used for energy — they're also essential for a healthy, balanced body. But it's all about balance — too many carbohydrates can be detrimental. "Your body's production of glucose and insulin can become abnormal, leading to health problems, poor food cravings, and weight gain." But, she said, "that does not mean that the answer is to eliminate [or significantly reduce] them."

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How Does the Keto Diet Work?

Lisa put it pretty simply: a ketogenic diet mimics starvation. The starvation effect causes the body to go into a metabolic state called "ketosis."

In our normal state, human bodies are sugar-driven: we eat carbohydrates, carbs are broken down into glucose, and glucose usually becomes energy, or it's stored as glycogen in liver and muscle tissue.

When you deprive your body of essential carbohydrate intake (Lisa noted that this is anything under 50 grams per day), then the liver goes into overdrive, because you don't have that carbohydrate-made glucose for energy. "The liver becomes the sole provider of glucose to feed your hungry organs — especially the brain, a greedy organ accounting for around 20 percent of total energy expenditure daily." Who knew the brain was so hungry?

The Effect of Cutting Carbs

Here's how it works: a very low-carb diet forces your body to use ketones instead of sugars for energy, which "is not advantageous, and can end up hurting you more than helping you," Lisa said.

Because the brain cannot directly use fat for energy, it needs a backup source when the carbohydrates are gone. No carbohydrates = a brain running on ketone. Ketones are produced by the liver using fatty acids from your food or body fat. Basically, your liver burns fat to make ketones.

These ketones — beta-hydroxybutyrate (BHB), acetoacetate, and acetone — are released into the bloodstream, used by the brain and other organs, and then shuttled into the "energy factory" (aka mitochondria) to be used as fuel (stay with us).

Any excess ketones exit the body via urine and breath, because according to Lisa, "they're volatile in nature." Because of this, those on a keto diet experience a characteristically sweet "keto breath."

What Are the Side Effects?

"Keto breath." As mentioned, keto breath is a thing, and it's not awesome.

Weak bones and stress fractures. Ketones are acidic, and one of their jobs is to pull phosphorous and calcium out of your bones. When ketones are your sole source of energy, you have a buildup, and thus, you deplete your phosphorous and calcium. This can lead to stress fractures and bone problems.

Headaches, bad mood, and bad memory. Because carbs are the "optimal energy source for the brain," the keto diet starves your brain of fuel. "When your brain is relying only on ketones, it gets foggy, headachey, and just not nearly as sharp as it could be on carbs," Lisa said. The result? Fatigue, moodiness, and possible anxiety.

Increased risk of disease. The ketogenic diet encourages you to eat an excess of fatty foods — and not the good kind of fat. "These are things that we KNOW — based on science — are very bad for you; bad for your heart, brain, diabetes risk, aging, and disease prevention," Lisa said. She noted that these bad things include saturated fat and omega-6 fats from butter, red meat, and cheese. "These are scientifically proven to be detrimental for your health."

Slowed metabolism. This is the opposite of what you want with a diet, correct? Correct. "The main reason a ketogenic diet is not good for weight loss is that it mimics starvation," Lisa said. In starvation mode, your body clings for dear life to every calorie you come near. As Lisa put it, "this is your metabolism coming to a screeching halt." In addition to a limited diet, bad mood, and missing pasta, you're also destroying your metabolism and putting yourself in a worse place than if you had just been eating carbs all along.

The balloon effect. Even worse, once you go back to your normal diet (because as Lisa put it, "a keto diet for life sounds like the worst thing ever"), you will balloon up. Yeah . . . seriously. "Your body will be so excited to see carbs again that it holds on to EVERYTHING and it will be much more difficult for you to lose weight again."

Does It Work For Anyone?

While Lisa says there's no reason for the average person to try the keto diet — "science supporting the ketogenic diet is either widely discredited or nonexistent" — it can work for children with epilepsy or someone who has suffered brain trauma or injury. There is some science to back up how a keto diet would work in those instances, but Lisa warns that those people should be under the supervision of both a doctor and a dietitian.

Consider where you're getting your information on keto. Is it from social media? Does your source have a degree? Are they versed in nutrition? Make sure you're getting the best information possible — this is your health we're talking about, after all!

In Summary . . .

"A balanced diet with a healthy mixture of carbs, good fats, and protein is key to weight loss and maintenance, and the best way to feel and look your best," Lisa said. We're happy to hear it, because we also really like pasta.

According to this dietitian (and many others), a ketogenic diet will slow down your metabolism, cause weight gain (after "the short-lived and promising drop in a few pounds"), induce foggy thinking, and incite a slew of other health threats, like weak bones and increased disease risk.